Rotor for induction motors



. Oct. 9, 1928.

F. P. LAUFFER ETAL ROTOR FOR INDUCTION MOTORS Filed March 2 1924 V lATTORNEY NVENTORS Frank P. Lauff'elt dc 5 amue/ C. Hog). BY

WITNESSES;

Patented Oct. 9 192 8.

UNITED STATES PATENT OFFICE.

FRANK P. IJAUFFER, 01E IRWIN, AND SAMUEL O. HOEY, OF WILKINSBURG,PENNSYL- VAN IA, ASSIGNORS TO WESTINGHOUSE ELECTRIC& MANUFACTURINGCOMPANY,

A CORPORATION OF PENNSYLVANIA.

ROTOR FOR INDUCTION MOTORS.

-App1ication filed March 2 9, 1924. Serial No. 702,733.

Our invention relates to rotors or armatures of dynamo-electricmachines, more especially to die-castmotors in which the end rings andconductor bars are formed integrally with the laminated body portion ofthe rotor member. d

It is among the objects of'our invention to provide a rotor havingspecially formed end ring portions for the purpose of expeditingmanufacture and producing such rotors in rellatively large quantitieswith uniform resu ts.

In a copending application, Serial No. 651,222, filed July 13, 1923,'isdescribed a process and apparatus for die casing the conductor membersof squirrel-cage rotors which utilizes insert metal strips for the endring portions to produce a uniform shrinkage of the cast metal, for thepurpose of eliminating the formation of bubbles and fallen surfaces.

Our-present invention is directed to means for accomplishing this resultwith greater simplicity and in a more positive'manner, in that weeliminate the metal stri inserts in the end rings and thereby allvariable factors that were introduced by the use thereof and caused bythe differences in size and characteristics of the metal.

We accomplish this result by utilizing a special jig or mold, having areservoir for molten metal associated therewith, in-which the endportions are formed in such manner as to produce a rotor casting havinga plurality of equally spaced recesses corres onding to a channelsection having radial y extending reinforcing'ribs. The channel sectioncomprises an end ring of uniform crosssection, which assures uniformcooling and setting of the molten metal, thereby eliminatingirregularities.

In the accompanying drawing constituting a part hereof and in which likereference characters designate like parts, I

Fig. 1 is a vertical sectional view of a diecasting mechanism forforming rotors in accordance with our invention.

Fig. 2 is an end elevational View of a rotor made in accordancetherewith, and

Fig. 3 is a cross-sectional View thereof "taken along the line III-IIIof Fig. 2.

Referring to Fig. 1, the illustrated casting device, WlllCh is shown forthe purpose of making clear the method of making a rotor, comprises ajig or die member 1 having a cylindrical matrix portion 2, a base plate3 and a pressure ring 4, the base plate 3 being mounted upon a cylinder5 that is supported on a base 6. A lever 7 is pivotally mounted upon anextending lug 8 on the member 5, and a plurality of communicating portholes 9 are provided in the lever 7 and the base plate 3. Yent holes 10areprov-ided in the pressure ring 4: to permit the escape of trappedgases during the casting ofthe metal. A piston 12 1s adapted to movevertically in the center opening 13 of the cylinder 5, which constitutesa reservoir for molten metal that is forced through the ports 9 into thedie 1.

The base plate and pressure ring 3 and 4:, respectively, are eachprovided with projections 15 corresponding in shape to the recesses 16in the end rings of the rotor shown in Figs. 2 and 3 to produce achannel section in the cast metal formed int-he die.

The rotor embodying the invention is cast by suitably positioning thelaminated portion 6r body 17 in the die between the base plate 3 andpressure ring 4, as shown in Fig. 1, whereby channel-shape spacesbetween the laminated body and the die member, in direct communicationwith the respective ends of vertical slots or openings 18 of the body17,

are provided. These spaces are filled by suitably actuating the piston12 to force the molten metal into the cylinder 5 upwardly through theport holes 9; and the resultant casting, as shown in Figs. 2 and 3,represents a complete squirrel-cage rotor having end rings 19 andintegral conductor bars 20.

The end rings 19 are of substantially channel-shaped cross-sectionhaving uniformly spaced radial reinforcing ribs 21. method ofconstruction produces a homogeneous grain structure 1n the metal, asthere is a uniform setting of the metal through the channel section andthe casting pressure exerted by the piston member 12 assures a uniformlydense structure of the conductor bars 20.

After the casting is formed, the lever 7 is actuated in a suitablemanner to break off the sprues formed in the ports 9, and the rotor maybe removed by unscrewing the handwheel-operated screw shaft 22. Anotherrotor is then inserted and the operation repeated.

It is evident from the foregoing description of our invention thatdie-cast rotors made This in accordance therewith may be formedexpeditiously and in production quantities with uniform results and thatsuch process is especially applicable to the manufacture of small rotorsof the squirrel-cage type.

Although we have described a specific embodiment of our invention itwill be obvious to those skilled in the art that various modificationsmay be made in the design and proportions of the rotor structure withoutdeparting from the principles herein set forth.

We claim as our invention 1. A rotor having its end rings and con-lductor bars integral therewith, said end rings being of substantiallychannel-shape in crosssection and provided with re-inforcing ribs.

2. A rotor having its end rings and conductor bars integral therewith,said end rings being of substantially channel-shape in crosssection andprovided with radial re-inforcing ribs in thechannel portions.

3. A rotor having its end rings and conductor bars integral therewith,said end rings being of substantially channel-shape in crosssection andprovided with uniformly spaced radial re-inforcing ribs.

4. A die-cast rotor having molecularly integral conductor bars and endrings, said end rings being provided with a plurality of recesses intheir outer sides at points opposite the ends of the conductor bars andhaving outer peripheries substantially uniform in cross-section.

In testimony whereof, we have hereunto subscribed our names this th dayof March,

FRANK P. LAUFFER. SAMUEL C. HOEY.

